Join in our Manta Ray Monitoring Program for FREE when you participate on a daily scuba diving trip to Hin Daeng and Hin Muang with Hidden Depths Diving.

During dives where manta rays are sighted, we take photographs of the distinctive markings on the underside of each ray. These photographs are then passed on to a conservation organization, together with information about conditions and behaviour. We brief divers on manta ray habits and behaviour, and encourage our divers to become involved in our conservation efforts. It is our aim to pass on our dedication for conservation to all our guests.

About Manta Rays

There are two species of manta ray, Manta alfredi (reef manta) and Manta birostris. The Manta birostris, otherwise known as the giant, oceanic or offshore manta ray, is the ray that visits us at the sites around Koh Lanta.

Manta rays eat zooplankton and have a number of feeding methods including swimming in the water column with an open mouth, feeding at the surface by gulping water or skimming the sea bed sucking up plankton. Observations have been made of mantas working together in large groups to form chains or patterns to aid feeding.

The Manta birostris can reach up to 7 metres or 23 feet. They have dark undersides with spots around the stomach area. The topside is predominantly black with triangular shaped shoulder patches. It also has the remnant of a stinging spine at the base of the tail.

Manta rays are ovoviviparous, which means that their young hatch in the womb and are then born alive. A female will give birth to 1-2 pups at a time. There is still much to learn about them, but it is thought that they can live up to 50 years.

Where we see them

We have the best chance of spotting manta rays at the dive sites of Hin Daeng and Hin Muang. Home to the deepest wall in Thailand, these sites are manta cleaning stations, and mantas visit there to have parasites removed. We visit the dive sites of Hin Daeng and Hin Muang twice a week in the hope of an encounter.

Diver Code of Conduct

Do not attempt to touch, ride, or chase a manta ray

Do not restrict normal movement or behaviour of the manta ray

Try to remain stationary to allow the manta ray to control the situation

Maintain a minimum distance of 3 metres from the manta ray

Do not undertake flash photography

Do not use underwater motorized diver propulsion vehicles

Threats

The greatest threat to manta rays is fishing. They have been targeted for their meat, liver oil and skin, but more recently their gill rakers have become much sought after in Traditional Chinese Medicine (TCM). Their natural predators are sharks and orcas, and shark bites are frequently observed and used to help identify individuals. Entanglement in fishing nets is another big issue as manta rays are unable to swim backwards and so cannot easily swim away.

The Red List of Threatened Species issued by the IUCN, the International Union for the Conservation of Nature, places manta rays in the vulnerable category. This is defined as:

VULNERABLE (VU) – A taxon is Vulnerable when it is not Critically Endangered or Endangered but is facing a high risk of extinction in the wild in the medium-term future

This is a database set up by Dr Andrea Marshall and her team at the Marine Megafauna Foundation in Mozambique to help monitor manta ray population numbers. A photo taken of the underside of the manta ray allows the teams to identify individuals and help track their movements.